Process and drum for looping annular anchoring structures in a process for building tyres for vehicle wheels

ABSTRACT

A process and a drum for looping annular anchoring structures in a process for building tyres for vehicle wheels includes: depositing a loop on a drum including a radially expandable/contractible intermediate annular portion and, in a position axially adjacent to the opposite axial ends of the intermediate annular portion, a pair of radially expandable/contractible lateral annular portions; associating an annular anchoring structure with a radially outer annular surface portion of the loop defined at the intermediate annular portion; and turning up each of opposite end edges of the loop on the annular anchoring structure through the lateral annular portions as a result of a thrusting stress imparted by a respective lateral annular portion of the pair of lateral annular portions because of a synchronous radial movement and a synchronous axial displacement of a respective plurality of circumferentially adjacent first angular sectors.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/158,596 filed on Sep. 23, 2016, which is a national phase applicationbased on PCT/162015/052105, filed Mar. 23, 2015, and claims the priorityof Italian Patent Application No. MI2014A000489, filed Mar. 24, 2014,the content of each application being incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a process for looping annular anchoringstructures in a process for building tyres for vehicle wheels.

The invention also relates to a drum which can be used to carry out theaforementioned process.

Description of the Related Art

The process and the drum of the invention are preferably used inbuilding tyres for automobiles, more specifically in building thecarcass structures of such tyres.

Hereafter, the term “loop” is used to indicate an annular elementcomprising one or more thread-like reinforcing elements that aresubstantially parallel to each other, such as textile or metallic cords,possibly incorporated in, or coated with, a layer of elastomericmaterial, such an annular element being obtained by cutting to size aband-like element and joining together a head portion and a tail portionof such a band-like element.

The term “elastomeric material” is used to indicate a compositioncomprising at least one elastomeric polymer and at least one reinforcingfiller. Preferably, such a composition also comprises additives like,for example, a cross-linking agent and/or a plasticizer. Thanks to thepresence of the cross-linking agent, such a material can be cross linkedthrough heating, so as to form the end product.

The terms “radial” and “axial” and the expressions “radiallyinner/outer” and “axially inner/outer” are used with reference to theradial direction and to the axial (or longitudinal) direction of a tyreor of a drum used for looping the annular anchoring structures of tyres.The terms “circumferential” and “circumferentially”, on the other hand,are used with reference to the annular extension of the aforementionedtyre/drum.

A tyre for vehicle wheels generally comprises a carcass structurecomprising at least one carcass ply formed of reinforcing cords embeddedin a matrix of elastomeric material. The carcass ply has end edgesrespectively engaged with annular anchoring structures. The latter arearranged in the areas of the tyre usually identified by the name “beads”and each of them is normally formed by a substantially circumferentialannular insert on which at least one filling insert is applied, in aradially outer position. The annular inserts are usually identified as“bead cores” and have the task of keeping the tyre firmly fixed to theanchoring seat specifically provided in the rim of the wheel, thuspreventing, in operation, the radially inner end edge of the tyre comingout from such a seat.

Specific reinforcing structures (such reinforcing structures being knownin the field of tyres by the term “loops”) having the function ofimproving the torque transmission to the tyre may be provided at thebeads. The region of the beads is, indeed, particularly active in thetransmission of torque from the rim to the tyre during acceleration andbraking and, therefore, the provision of suitable reinforcing structuresin such an area ensures that the transmission of torque takes place withthe maximum possible reactivity.

A crown structure is associated in a radially outer position withrespect to the carcass ply. The crown structure comprises a beltstructure and, in a radially outer position with respect to the beltstructure, a tread band made from elastomeric material.

The belt structure comprises one or more belt layers arranged radiallyone on top of the other and having reinforcing textile or metallic cordswith a crossed orientation and/or an orientation substantially parallelto the direction of circumferential extension of the tyre.

On the side surface of the carcass structure, each extending from one ofthe side edges of the tread band up to the respective annular anchoringstructure to the beads, respective sidewalls made of elastomericmaterial are applied.

EP 0 647 522 describes a looping process comprising at first thedeposition of a loop on the outer annular surface of a plurality ofcentral sectors of a service drum, said central sectors beingdistributed circumferentially one after the other. The annular anchoringstructure is then positioned on the loop. The central sectors are thenmoved radially until the loop is made to adhere to the radially innersurface of the annular anchoring structure. The loop is then turned uparound the annular anchoring structure as a result of the thrustingaction exerted on the loop portions that extend axially from oppositesides with respect to the annular anchoring structure from the lobes ofan air chamber, such lobes being obtained, upon inflating said airchamber, by squashing said air chamber with a pair of auxiliary supportelements arranged in a radially outer position with respect to the airchamber.

WO 2010/116253, in the name of the Applicant, describes a loopingprocess comprising at first setting a service drum to a predeterminedradial dimension as a function of the fitting diameter of the tyre to bemanufactured. The loop is then deposited on the drum and the annularanchoring structure is positioned on the drum in a radially outerposition with respect to the loop. Then the drum is radially expandeduntil the annular anchoring structure is locked in position. The drum isthen set in rotation about its rotation axis and, during such rotation,the looping of the annular anchoring structure is carried out through apair of turning rollers able to be moved with respect to the drum bothalong a direction parallel to the rotation axis of the drum and along adirection perpendicular to the aforementioned axis.

SUMMARY OF THE INVENTION

The Applicant has observed that the provision of a service drum that isat least partially radially expandable/contractible, as described in EP0 647 522 and WO 2010/116253, makes it possible to loop in sequenceannular anchoring structures of different size configured for tyreshaving different fitting diameters, consequently increasing theflexibility of production without reducing the productivity of theplant.

The Applicant has, however, observed that carrying out a process of thetype described in EP 0 647 522 is problematic in those cases in whichthe loop comprises metallic cords. Indeed, in these cases an earlydeterioration of the air chamber occurs as a result of the sliding ofthe air chamber on the metallic cords of the loop. It is thus necessaryto replace the air chamber quite frequently, with consequent problems ofcost and time.

The Applicant has also observed that the looping process described in WO2010/116253 necessarily requires the rotation of the drum (and thereforeof the annular anchoring structure) during the turning up of theopposite end edges of the loop on the annular anchoring structure. Thiscan lead to an undesired deformation of the annular anchoring structure,at the expense of the quality of the looping.

The Applicant has also observed that the looping processes of the typedescribed in EP 0 647 522 and WO 2010/116253 both require the use ofmembers which are external with respect to the drum (reference is madein particular to the two auxiliary support elements of EP 0 647 522 andthe two turning rollers of WO 2010/116253). The presence of suchexternal members with respect to the drum can constitute a problem whenthere are constraints in terms of bulk and/or layout.

The Applicant has perceived the need to provide a looping process inwhich members incorporated in the drum are used, so as not to worryabout possible constraints in terms of bulk and/or layout, and whichdoes not require the rotation of the annular anchoring structures duringthe turning of the loop, so as not to deform the annular anchoringstructures.

In this respect, the Applicant has realised that it may be advantageousto use a radially expandable/contractible drum (thus suitable forlooping in sequence annular anchoring structures of different size)provided with turning members other than air chambers (so as to be ableto work even with loops comprising metallic cords).

The Applicant has found that by providing a drum comprising a radiallyexpandable/contractible intermediate annular portion and a pair ofradially expandable/contractible lateral annular portions arranged onopposite sides with respect to the intermediate annular portion and eachcomprising a plurality of circumferentially adjacent angular sectorswhich can be moved in a synchronous manner both radially and axially, itis possible to achieve both the desired radial expansion/contraction ofthe drum, to allow the looping of annular anchoring structures ofdifferent diameter, and the desired turning up of the loop throughturning members incorporated in the drum.

The present invention therefore relates, in a first aspect thereof, to aprocess for looping annular anchoring structures in a process forbuilding tyres for vehicle wheels.

Preferably, it is foreseen to deposit a loop on a drum comprising aradially expandable/contractible intermediate annular portion and, in aposition axially adjacent to the opposite axial ends of saidintermediate annular portion, a pair of radially expandable/contractiblelateral annular portions.

Preferably, it is foreseen to associate an annular anchoring structurewith a radially outer annular surface portion of said loop defined atsaid intermediate annular portion.

Preferably, it is foreseen to turn up each of opposite end edges of saidloop on said annular anchoring structure through said lateral annularportions.

Preferably, each of said end edges is turned up as a result of athrusting stress imparted by a respective lateral annular portion ofsaid pair of lateral annular portions because of a synchronous radialmovement and a synchronous axial displacement of a respective pluralityof circumferentially adjacent first angular sectors.

The Applicant believes that the process described above, making use of adrum having a radially expandable/contractible intermediate annularstructure, allows to loop in sequence annular anchoring structures ofdifferent size. Moreover, thanks to the fact that the turning up of theend edges of the loop on the annular anchoring structure is achieved asa result of the synchronous radial and axial movement of a plurality ofangular sectors of the drum arranged at opposite lateral annularportions of the drum, it is possible to carry out the looping of theannular anchoring structures, even in the presence of constraints interms of bulk and layout, with loops of any type (thus also with loopscomprising metallic cords) and without any risk of deforming the annularanchoring structure.

In a second aspect thereof, the present invention relates to a drum forlooping annular anchoring structures in a process for building tyres forvehicle wheels.

Preferably, a radially expandable/contractible intermediate annularportion is provided.

Preferably, a pair of radially expandable/contractible lateral annularportions is provided in a position axially adjacent to the oppositeaxial ends of said intermediate annular portion.

Preferably, each lateral annular portion of said pair of lateral annularportions comprises a plurality of circumferentially adjacent firstangular sectors capable of being moved radially and axiallysynchronously with each other.

According to the Applicant, such a drum makes it possible to carry outthe looping process described above, thus allowing all of the advantagesdiscussed above to be achieved.

The present invention, in at least one of the aforementioned aspects,can have at least one of the following preferred characteristics, takenindividually or in combination with each other.

Preferably, the synchronous axial displacement of said first angularsectors is carried out simultaneously with said radial movement. In thisway it is possible to obtain a progressive and gradual deposition of theend edges of the loop on the side surfaces of the annular anchoringstructure, with consequent advantages in terms of deposition quality,speed of execution and quick set-up.

Preferably, said axial displacement is achieved as a result of an axialelastic thrust exerted on each of said first angular sectors.Advantageously, the first angular sectors thus tend to thrust the endedges of the loop against the side surface of the annular anchoringstructure, in this way contributing to obtain the desired depositionquality and speed of execution. Moreover, since it is an elastic thrust,and therefore reversible, it is extremely easy to provide for axiallymoving the first angular sectors away from the annular anchoringstructure at the end of the turning up of the end edges of the loop toallow the annular anchoring structure just looped to be picked up andtaken away.

In preferred embodiments of the invention, before depositing said loop,at least said intermediate annular portion is radially expanded up toreach an operating diameter that is selected depending on a fittingdiameter of a tyre to be built. There is therefore the possibility oflooping annular anchoring structures intended for tyres having differentfitting diameters, in this way achieving advantageous process economy.

Preferably, associating said annular anchoring structure comprisespositioning said annular anchoring structure in a radially outerposition with respect to said loop at said intermediate annular portion.This is made irrespective of the diameter of the annular anchoringstructure.

Advantageously, the aforementioned positioning of the annular anchoringstructure is achieved using a transfer member configured to keep theannular anchoring structure centred with respect to the middle of thedrum and to leave the radially inner surface of the annular anchoringstructure completely free.

More preferably, associating said annular anchoring structure comprisesradially expanding at least said intermediate annular portion until aradial thrust is exerted on a radially inner surface of said annularanchoring structure. In this way an operative configuration is achievedin which the annular anchoring structure is held in position on the drumwithout the need to foresee specific holding members outside the drum.In this operative configuration the aforementioned transfer member canleave the annular anchoring structure to allow the deposition of the endedges of the loop on the opposite side surfaces of the annular anchoringstructure.

In preferred embodiments of the invention, said radial thrust is anelastic thrust. Such a provision makes it possible to obtain the desiredholding of the annular anchoring structure on the drum in an extremelysimple and effective manner irrespective of the diameter of the annularanchoring structure. Moreover, since it is an elastic thrust, andtherefore reversible, it is extremely easy to also detach the annularanchoring structure from the drum at the end of the looping process.

Preferably, the radial expansion of at least said intermediate annularportion is carried out simultaneously with at least part of the radialmovement of said first angular sectors. This contributes to achieve thedesired process economy and speed of execution.

Preferably, the radial expansion of at least said intermediate annularportion is achieved as a result of the synchronous radial movement of aplurality of circumferentially adjacent second angular sectors.

Preferably, the radial movement of each of said second angular sectorsis obtained as a result of an elastic thrust exerted on each of saidsecond angular sectors.

In preferred embodiments of the invention, at the end of the turning upof said opposite end edges of said loop, said first angular sectors areaxially moved away from said annular anchoring structure. This is madein order to allow the subsequent removal of the looped annular anchoringstructure.

Preferably, said first angular sectors are locked in a distal axialposition with respect to said annular anchoring structure. Such aprovision facilitates the aforementioned removal.

Even more preferably, said first angular sectors are radially contractedafter said first angular sectors are locked at said distal axialposition. Advantageously, following such radial contraction the annularanchoring structure just looped can be picked up by a suitable removaldevice, which then takes care of removing the looped annular anchoringstructure. Advantageously, the actuation of the aforementioned radialcontraction only after the axial locking of the first angular sectorsmakes it possible to eliminate any possible contact between the firstangular sectors and the loop just deposited on the side surfaces of theannular anchoring structure. Such contact could indeed cause anundesired detachment of the end edges of the loop from the side surfacesof the annular anchoring structure.

Preferably, at the end of the radial contraction of said first angularsectors, said first angular sectors are unlocked from said distal axialposition. In this way, the drum goes back to the initial configuration,ready to proceed with the looping of another annular anchoringstructure.

In preferred embodiments thereof, said intermediate annular portioncomprises a plurality of circumferentially adjacent second angularsectors radially movable synchronously with each other.

Preferably, said intermediate annular portion comprises, in a radiallyinner position with respect to each of said second angular sectors, afirst elastic element acting to radially thrust a respective secondangular sector.

Preferably, each of said first angular sectors is slidably associatedwith a radially outer surface of a radially movable support body.

Preferably, each of said second angular sectors is kept in a radialcontracted position against said radial thrust by a pair of axiallyopposite first angular sectors.

In preferred embodiments of the invention, each of said first angularsectors comprises a second elastic element acting to axially thrust anaxially outer end thereof.

Preferably, each of said first angular sectors comprises a contactelement associated with an axially inner end thereof. Preferably, saidcontact element is made from deformable or elastic material. In aspecific embodiment thereof, said contact element is a roller.

Preferably, the drum comprises a locking assembly for stopping the axialmovement of said first angular sectors.

In preferred embodiments thereof, said locking assembly comprises a pairof holes formed on said radially outer surface of said support body.

Preferably, said locking assembly also comprises a pin associated with arespective first angular sector.

More preferably, said locking assembly comprises a third elastic elementacting between said pin and the respective first angular sector so that,in an axial locking condition of said first angular sector, a free endportion of said pin is housed inside one of said holes and, in an axialunlocking condition of said first angular sector, said free end portionof said pin is outside of said hole.

In preferred embodiments thereof, said locking assembly comprises, at anaxially outer end of said first angular sectors, a contrast ring.

Preferably, said locking assembly further comprises a plurality ofbalancing levers, each of which having a first end pivoted at an axiallyouter end of a respective first angular sector and a second endconfigured to cooperate with said contrast ring when said first angularsector is in a condition of maximum expansion.

Preferably, when said second end of said balancing lever is not incontact with said contrast ring said first angular sector is in saidaxial unlocking condition and when said second end of said balancinglever is in contact with said contrast ring said first angular sectorreaches said axial locking condition.

Preferably, the drum comprises an unlocking assembly for unlocking theaxial movement of said first angular sectors.

More preferably, said unlocking assembly comprises a spigot configuredto expel said free end portion of said pin from said hole when saidfirst angular sector is radially contracted until a condition of maximumcontraction is reached.

Even more preferably, said spigot is arranged in a radially outerposition with respect to a guide bar provided for guiding the radialmovement of said first angular sector.

Preferably, a screw-lead nut coupling is provided at each of saidopposite axial ends of said intermediate annular portion.

More preferably, a plurality of levers are used, each of which having afirst end pivoted at a respective lead nut and a second end pivoted at arespective first angular sector.

Preferably, said screw comprises a first axial portion with aright-handed thread and a second axial portion with a left-handedthread, or vice-versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention willbecome clearer from the following detailed description of preferredembodiments thereof, made with reference to the attached drawings. Insuch drawings:

FIG. 1 is a schematic perspective view of a drum in accordance with thepresent invention;

FIG. 2 is a schematic radial section view of a portion of the drum ofFIG. 1 in a first operative configuration thereof;

FIG. 3 is a schematic partial section view of the portion of drum ofFIG. 1 in a subsequent operative configuration thereof;

FIG. 4 is a schematic partial section view of the portion of drum ofFIG. 1 in an operative configuration subsequent to that of FIG. 3;

FIG. 5 is a schematic partial section view of the portion of drum ofFIG. 1 in an operative configuration subsequent to that of FIG. 4;

FIG. 6 is a schematic partial section view of the portion of drum ofFIG. 1 in an operative configuration subsequent to that of FIG. 5;

FIG. 7 is a schematic partial section view of the portion of drum ofFIG. 1 in an operative configuration subsequent to that of FIG. 6;

FIG. 8 is a schematic partial section view of the portion of drum ofFIG. 1 in an operative configuration subsequent to that of FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, reference numeral 100 wholly indicates an exemplifyingembodiment of a drum for looping annular anchoring structures inaccordance with the present invention. Such looping is carried out in aprocess for building tyres for vehicle wheels, preferably for automobilewheels.

Preferably, the annular anchoring structures, once looped, are used inbuilding the carcass structures of the aforementioned tyres. Inparticular, they are positioned in the beads of the tyre and areintended to keep the tyre firmly fixed to the anchoring seatspecifically provided in the rim of the vehicle wheel.

An example of an annular anchoring structure intended to be looped onthe drum 100 is shown in FIG. 3 and is indicated with reference numeral10.

The annular anchoring structure 10 comprises a substantiallycircumferential annular insert 11, also called bead core, and a fillinginsert 12. The latter is associated with the substantiallycircumferential annular insert 11 in a radially outer position withrespect to the latter.

The looping of the annular anchoring structure 10 comprises thedeposition of a loop 5 on the radially outer surface of the drum 100(FIG. 2), the positioning of the annular anchoring structure 10 in aradially outer position with respect to the drum 100 through a transfermember 500 (FIG. 3), the coupling of the loop 5 with the radially innersurface of the annular anchoring structure 10 (FIG. 4) and the turningup of the opposite edges 5 a, 5 b of such a loop 5 around the annularanchoring structure 10 so as to completely surround the latter (FIGS.5-7), thus forming a reinforced annular anchoring structure 15 (FIGS.6-8). Subsequently, the reinforced annular anchoring structure 15 ispicked up by a transfer member, which can for example be the sametransfer member 500 used to position the annular anchoring structure 10on the drum 100.

Preferably, at the end of the looping process the end portions of theend edges 5 a, 5 b of the loop 5 are offset in the radial direction, forexample by at least a few millimetres (preferably by about 5 mm).

The drum 100 can be part of a work station in which there are at leastone first storage member for storing annular anchoring structures 10 tobe looped and at least one second storage member for storing reinforcedannular anchoring structures 15. The aforementioned storage members canbe part of a handling line arranged close to the drum 100.

With reference to FIG. 1, the drum 100 extends concentrically to alongitudinal axis X-X.

The drum 100 comprises an intermediate annular portion 110 and, in aposition axially adjacent to the opposite axial ends of saidintermediate annular portion 110, a pair of lateral annular portions 120a, 120 b.

Both the intermediate annular portion 110 and the lateral annularportions 120 a, 120 b are radially expandable/contractible.

In particular, the intermediate annular portion 110 comprises aplurality of identical angular sectors 111, which are circumferentiallyadjacent and radially movable synchronously with each other.

Hereinafter, the angular sectors 111 will be identified as “intermediateangular sectors”. For the sake of simplicity of illustration, in FIG. 1the reference numeral 111 is associated with only one of theintermediate angular sectors.

Each of the lateral annular portions 120 a, 120 b comprises a pluralityof identical angular sectors 121 a, 121 b, which are circumferentiallyadjacent and radially movable synchronously with each other.

Hereinafter, the angular sectors 121 a, 121 b will be identified as“lateral angular sectors”. For the sake of simplicity of illustration,in FIG. 1 the reference numerals 121 a and 121 b are associated withonly one of the angular sectors of the lateral annular portion 120 a andwith only one of the angular sectors of the lateral annular portion 120b, respectively.

The synchronous radial movement of the lateral angular sectors 121 a issynchronous with the synchronous radial movement of the lateral angularsectors 121 b, as described more clearly hereinafter.

The drum 100 also comprises, in a radially inner position with respectto the intermediate angular sectors 111 and to the lateral angularsectors 121 a, 121 b, a sleeve 101 extending coaxially to thelongitudinal axis X-X.

The sleeve 101 is preferably fixed canti-levered on a bearing structurethat is not illustrated, so as to allow the annular anchoring structure100 to be placed in a radially outer position with respect to the drum100.

As shown in FIG. 2, inside the sleeve 101, and coaxially to thelongitudinal axis X-X, a worm screw 102 is provided. The worm screw 102has a first right-handed axial portion 102 a and, on the opposite sidewith respect to a middle plane M of the drum 100, a second left-handedaxial portion 102 b.

The screw 102 is supported inside the sleeve 101 by a pair of rollingbearings, not shown. Such a screw 102 can be set in rotation by asuitable motor group, also not shown.

The right-handed axial portion 102 a (or the left-handed one 102 b) isdefined in a radially inner position with respect to the lateral angularsectors 121 a, whereas the left-handed axial portion 102 b (or theright-handed one 102 a) is defined in a radially inner position withrespect to the lateral angular sectors 121 b.

With reference to FIG. 1, the drum 100 also comprises, in an axiallyouter position with respect to the lateral annular portions 120 a, 120b, respective contrast rings 200 a, 200 b.

Each contrast ring 200 a, 200 b is fixedly associated with the sleeve101 through a plurality of axial brackets 201 a, 201 b and a pluralityof radial brackets 202 a, 202 b. Preferably, the axial brackets 201 a,201 b and the radial brackets 202 a, 202 b are arranged in an axiallyouter position with respect to the respective contrast ring 200 a, 200b.

Each axial bracket 201 a, 201 b has an axial end associated with thecontrast ring 200 a, 200 b and an opposite axial end associated with arespective radial bracket 202 a, 202 b, in turn fixedly associated withthe sleeve 101.

The axial brackets 201 a, 201 b can be fixedly associated with therespective contrast ring 200 a, 200 b or can be removably associatedwith the contrast ring 200 a, 200 b.

In the exemplifying embodiment of the drum 100 shown in FIG. 1, at eachcontrast ring 200 a, 200 b there are three axial brackets 201 a, 201 band three radial brackets 202 a, 202 b, all circumferentially spacedapart by 120°.

Again with reference to the exemplifying embodiment of FIG. 1, eachradial bracket 202 a, 202 b comprises a plurality of weight reductionholes 203 a, 203 b (four in the illustrated embodiment) aligned in theradial direction.

For the sake of simplicity of illustration, reference numeral 203 a, 203b is associated with only one hole of only one radial bracket 202 a, 202b.

Preferably, the radial brackets 202 a, 202 b are tapered progressivelymoving in the radially outward direction.

FIGS. 2-8 show the mutual arrangement of an intermediate angular sector111 and of the two lateral angular sectors 121 a, 121 b arranged onaxially opposite sides with respect to the intermediate angular sector111 in different operative configurations of the drum 100. The samemutual arrangement can be found, in each of the aforementioned operativeconfigurations, at each of the other circumferentially adjacent angularsectors 111, 121 a and 121 b of the drum 100.

The lateral angular sectors 121 a and 121 b are arranged in amirror-like fashion with respect to the middle plane M of the drum 100.

With reference to FIGS. 2-8, each intermediate angular sector 111preferably comprises an inverted T-shaped body; it thus preferablycomprises a radially outer portion having a predetermined axial lengthand a radially inner portion having a greater axial length than that ofthe radially outer portion.

A respective elastic element 113, acting in radial thrust on theintermediate angular sector 111, is arranged in a radially innerposition with respect to the intermediate angular sector 111.

Preferably, the elastic element 113 is a compression spring.

In the specific exemplifying embodiment illustrated in FIGS. 2-8, asupport body 122 is provided in a radially inner position with respectto each pair of axially adjacent lateral angular sectors 121 a, 121 b.Such a support body 122 comprises two support body portions 122 a, 122 barranged symmetrically on axially opposite sides with respect to themiddle plane M of the drum 100. The support body portion 122 a isarranged in a radially inner position with respect to the lateralangular sector 121 a and the support body portion 122 b is arranged in aradially inner position with respect to the lateral angular sector 121b.

Each support body portion 122 a, 122 b is provided with a hole 123 a,123 b extending in the radial direction (FIGS. 5-7). The hole 123 a, 123b houses, through a sliding coupling, a respective guide bar 124 a, 124b fixedly associated with the sleeve 101 and extending in the radialdirection. As a result of the aforementioned sliding coupling thesupport body 122 can move radially with respect to the sleeve 101.

The hole 123 a, 123 b has a radially outer portion with reduceddiameter, which hereafter is called hole 123 a′, 123 b′.

The guide bar 124 a, 124 b has a spigot 125 a, 125 b on a radially outersurface thereof (FIGS. 5-7).

In the operative configurations of the drum 100 in which the lateralangular sectors 121 a, 121 b are radially contracted (FIGS. 2, 3 and 8),the spigot 125 a, 125 b is housed in the hole 123 a′, 123 b′. In theaforementioned figures, such a specific configuration is indicated withthe following string of reference numerals: 125 a=123 a′, 125 b=123 b′.

An end portion of a respective lever 140 a, 140 b is pivoted on eachsupport body portion 122 a, 122 b. The opposite end portion of the lever140 a, 140 b is pivoted at a flange 145 a, 145 b fixedly associated witha lead nut 146 a, 146 b coupled with a respective axial portion 102 a,102 b of the screw 102.

As a result of the screw-lead nut coupling and of the sliding couplingbetween support body 122 and guide bar 124 a, 124 b described above, arotation of the screw (for example in the clockwise direction, ifstarting from the operative configuration of FIG. 2 and in theanti-clockwise direction if starting from the operative configuration ofFIG. 7) produces a synchronous axial displacement of the flanges 145 a,145 b in opposite directions (in particular the flanges 145 a, 145 bmoves one towards the other if starting from the operative configurationof FIG. 2, and the flanges 145 a, 145 b move away from one other ifstarting from the operative configuration of FIG. 7) and consequently asynchronous radial displacement of the support body 122 (in particular aradial expansion of the lateral annular portions 120 a, 120 b ifstarting from the operative configuration of FIG. 2, and a radialcontraction of the lateral annular portions 120 a, 120 b if startingfrom the operative configuration of FIG. 7).

As shown in FIG. 2, the support body 122, comprises, in a radially innerposition, a shoulder 130 on which a radially inner end of the elasticelement 113 is arranged in abutment. Such an elastic element 113 is thusheld in compression between the shoulder 130 and the radially innersurface of the intermediate angular sector 111.

Each lateral angular sector 121 a, 121 b comprises, at an axially innerend thereof, a contact element 127 a, 127 b preferably made fromdeformable or elastic material. For the sake of simplicity ofillustration the reference numerals 127 a and 127 b are reproduced onlyin FIGS. 4 and 6-8.

The contact elements 121 a, 121 b ensure the continuity of surfacecontact between loop 5 and annular anchoring structure 10 during thelooping of the latter.

A respective elastic element 128 a, 128 b acts on an axially outer endof each lateral angular sector 121 a, 121 b. Such an elastic element 128a, 128 b axially thrusts the respective lateral angular sector 121 a,121 b towards the middle plane M of the drum 100.

Preferably, the elastic element 128 a, 128 b is a compression springhoused in an axial seat 129 a, 129 b formed on an axially outer endportion of the lateral angular sector 121 a, 121 b.

As shown in FIG. 3, the support body 122 comprises, in a radially outerposition, a pair of shoulders 131 a, 131 b. An axially outer end of arespective elastic element 128 a, 128 b goes into abutment on eachshoulder 131 a, 131 b. Each elastic element 128 a, 128 b is thus held incompression between the shoulder 131 a, 131 b and the axially outer endportion of the lateral angular sector 121 a, 121 b.

In the operative configuration of the drum 100 shown in FIGS. 2, 3 and8, as a result of the axial thrust exerted by the elastic element 128 a,128 b on the lateral angular sector 121 a, 121 b, the axially inner endportion of each of the two opposite lateral angular sectors 121 a, 121 bis in axial abutment against the radially outer portion of theintermediate angular sector 111, thus counteracting the elastic thrustexerted on the lateral angular sectors 121 a, 121 b by the respectiveelastic elements 128 a, 128 b. In such an operative configuration theaxially inner end portion of the two opposite lateral angular sectors121 a, 121 b is also in radial abutment against the radially innerportion of the intermediate angular sector 111, thus counteracting theelastic thrust exerted on the intermediate angular sector 111 by theelastic element 113 and thus keeping the intermediate angular sector 111in a position of radial contraction. In this way both the axialdisplacement of the lateral angular sectors 121 a, 121 b towards themiddle plane M of the drum 100 and the radial expansion of theintermediate angular sector 111 are prevented. Such a radial expansioncan, on the other hand, take place, as a result of the thrusting actionexerted by the elastic element 113, because of the radial expansion ofthe lateral angular sectors 121 a, 121 b.

With reference to FIG. 2, each lateral angular sector 121 a, 121 b alsocomprises a radial blind hole 150 a, 150 b that is open at the radiallyinner surface thereof. The blind hole 150 a, 150 b houses, in a radiallyouter position, an elastic element 151 a, 151 b and, in a radially innerposition, a pin 152 a, 152 b. The elastic element 151 a, 151 b thruststhe pin 152 a, 152 b in the radial direction towards the outside of theblind hole 150 a, 150 b.

Preferably, the elastic element 151 a, 151 b is a compression spring.

In the operative configurations of the drum 100 shown in FIGS. 2-6 and8, the pin 152 a, 152 b is misaligned with respect to (or outside of)the hole 123 a′, 123 b′; therefore, the free end radially inner portionof the pin 152 a, 152 b abuts against the radially outer surface of thesupport body 122, which thus exerts a contrast action to the thrustexerted by the elastic element 151 a, 151 b on the pin 152 a, 152 b. Insuch operative configurations the lateral angular sector 121 a, 121 b isfree to slide axially on the support body 122.

The axially outer end of each lateral angular sector 121 a, 121 b ispivoted at an end portion of a respective balancing lever 160 a, 160 b.The latter has, at an opposite free end portion thereof, a roller 161 a,161 b which can rotate about a rotation axis perpendicular to the axialand radial directions of the drum 100.

The roller 161 a, 161 b is arranged in a radially inner position withrespect to the contrast ring 200 a, 200 b. Such a roller 161 a, 161 b isintended to abut on the contrast ring 200 a, 200 b when the lateralangular sector 121 a, 121 b is in a condition of maximum expansion (FIG.7).

During looping, each lever 160 a, 160 b rotates about two axially outerpivots formed in the support body 122, moving the lateral angularsectors 121 a and 121 b apart from one another until the pins 152 a and152 b, as a result of the thrust exerted by the elastic element 151 a,151 b, go inside the holes 123 a and 123 b. Such a specificconfiguration is indicated in FIG. 7 with the following string ofreference numerals: 152 a=123 a′, 152 b=123 b′.

The two lateral angular sectors 121 a and 121 b are thus locked in anaxially distal position with respect to the middle plane M of the drum100; this position ensures no interference between the contact elements127 a, 127 b with the loop 5 turned up on the annular anchoringstructure 10, during the contraction of the drum 100. Such a specificconfiguration is indicated in FIG. 7 with the following string ofreference numerals: 152 a=123 a′, 152 b=123 b′.

Each assembly comprising the elastic element 151 a, 151 b, the pin 152a, 152 b, the hole 123 a′, 123 b′, the balancing lever 160 a, 160 b andthe contrast ring 200 a, 200 b defines, in the drum 100, a respectiveassembly for stopping the axial movement of a respective lateral angularsector 121 a, 121 b with respect to the support body 122. Such a lockingassembly is active in the operative configuration of the drum 100 shownin FIG. 7, corresponding to a condition of maximum expansion of the drum100.

The axial movement of each lateral angular sector 121 a, 121 b withrespect to the support body 122 is once again possible when, startingfrom the operative configuration of FIG. 7, after the radial contractionof the support body 122 the spigot 125 a, 125 b expels the pin 152 a,152 b from the hole 123 a′, 123 b′, in this way reaching the operativeconfiguration shown in FIG. 8.

Each assembly comprising the elastic element 151 a, 151 b, the pin 152a, 152 b, the hole 123 a′, 123 b′ and the spigot 125 a, 125 b defines,in the drum 100, a respective unlocking assembly for unlocking the axialmovement of a respective lateral angular sector 121 a, 121 b withrespect to the support body 122.

A preferred embodiment of a process for looping annular anchoringstructures 10 in a process for building tyres for vehicle wheels willnow be described. Such a process can be carried out using the drum 100described above.

Initially, the drum 100 is in a configuration of maximum radialcontraction, shown in FIG. 1.

The drum 100 is thus radially expanded up to reach an operating diameterthat is selected depending on a fitting diameter of a tyre to be built.

Such a radial expansion is achieved as a result of the synchronous andsimultaneous radial movement of the intermediate angular sectors 111 andof the lateral angular sectors 121 a, 121 b. This occurs following arotation of the screw 102. Such a rotation produces a synchronous axialdisplacement of the lead nuts 146 a, 146 b towards one another and, as aresult of the consequent displacement of the levers 140 a, 140 b, asynchronous radial displacement apart from one another (i.e. in aradially outward direction) of the support bodies 122 a, 122 b andtherefore of the lateral angular sectors 121 a, 121 b associated withthem. Such a synchronous radial displacement in turn allows thesynchronous radial displacement apart from one another of theintermediate angular sectors 111 as a result of the elastic thrustexerted by the elastic element 113.

The drum 100 is at this point set in rotation about the longitudinalaxis X-X by a suitable control device. During such a rotation, the screw102 is decoupled from the drum and does not rotate, so as to prevent thedrum 100 from expanding or contracting radially any further.

During the rotation of the drum 100 the loop 5 is deposited flat on theradially outer surface of the lateral angular sectors 121 a, 121 b andof the intermediate angular sectors 111 (FIG. 2).

At the end of the deposition of the loop 5 the end edge 5 a of the loopis positioned on at least part of each lateral angular sector 121 a, theend edge 5 b of the loop 5 is positioned on at least part of eachlateral angular sector 121 b and an intermediate portion of the loop 5is positioned on each intermediate angular sector 111. Preferably, theposition of the loop 5 is asymmetrical with respect to the middle planeM of the drum 100.

At this point, the transfer member 500 carries an annular anchoringstructure 10 in a radially outer position with respect to theintermediate portion of the radially outer annular surface of the loop 5(FIG. 3). The transfer member 500 holds the annular anchoring structure10 at a lateral surface of the substantially circumferential annularinsert 11, for example as a result of a magnetic attraction or bysuction.

The annular anchoring structure 10 is carried by the transfer member 500in a centred position with respect to the middle plane M of the drum 100and is held in such a position while the drum 100 is radially expanded.Such an expansion proceeds until the drum 100 exerts a predeterminedradial thrust on the radially inner surface of the annular anchoringstructure 10. The radial expansion of the drum 100 is achieved as aresult of the synchronous radial movement of the lateral angular sectors121 a, 121 b and of the intermediate angular sectors 111, as describedabove.

At this point the transfer member 500 leaves the annular anchoringstructure 10 and the turning up of the end edges 5 a, 5 b on theopposite lateral surfaces of the annular anchoring structure 10 canbegin (FIGS. 4-6). Such a turning up is achieved as a result of theradial expansion of only the lateral annular portions 120 a, 120 b ofthe drum 100 and of the simultaneous synchronous axial movement of thelateral angular sectors 121 a, 121 b.

The radial expansion of the lateral annular portions 120 a, 120 b isobtained as a result of the synchronous radial movement of only thelateral angular sectors 121 a, 121 b.

The synchronous radial movement of the lateral angular sectors 121 a,121 b is obtained as described above.

The radial movement of the intermediate angular sectors 111, on theother hand, is prevented by the radial contrast force exerted by theannular anchoring structure 10 against the elastic thrust of the elasticelement 113, which contracts (FIGS. 5 and 6).

The simultaneous synchronous axial movement of the lateral angularsectors 121 a, 121 b is obtained, while the lateral angular sectors 121a, 121 b radially displace outwards, as a result of the axial thrustexerted by the elastic element 128 a, 128 b against the annularanchoring structure 10.

During the radial movement and the simultaneous axial movement of thelateral angular sectors 121 a, 121 b, the contact elements 127 a, 127 bthrust the end edges 5 a, 5 b of the loop 5 against the lateral surfacesof the annular anchoring structure 10, until the operative configurationshown in FIG. 6 is reached, in which the annular anchoring structure 10is completely surrounded by the loop 5. A reinforced annular anchoringstructure 15 is thus obtained.

A further synchronous radial movement of the lateral angular sectors 121a, 121 b is at this point prevented by the contact between rollers 161a, 161 b and respective contrast rings 200 a, 200 b. In particular, theradial thrust of the rollers 161 a, 161 b on the contrast rings 200 a,200 b causes a rolling of the rollers 161 a, 161 b on the radially innersurface of the contrast rings 200 a, 200 b, a consequent displacement ofthe balancing levers 160 a, 160 b and a consequent axial displacement ofthe lateral angular sectors 121 a, 121 b away from the reinforcedannular anchoring structure 15, overcoming the elastic thrust exerted bythe elastic elements 128 a, 128 b.

During such axial displacement the pins 152 a, 152 b of the lateralangular sectors 121 a, 121 b, thrusted by the respective elasticelements 151 a, 151 b, slide on the radially outer surface of thesupport body 122 until the operative configuration shown in FIG. 7 isreached, in which the pins 152 a, 152 b go inside the holes 123 a′, 123b′, preventing any further axial displacement of the lateral angularsectors 121 a, 121 b.

At this point the direction of rotation of the screw 102 is reversed,thus obtaining a radial contraction of the lateral annular portions 120a, 120 b of the drum 100 as a result of the synchronous radial movementof the lateral angular sectors 121 a, 121 b in a radially inwarddirection.

The aforementioned radial contraction proceeds until the spigots 125 a,125 b provided on the guide bars 124 a, 124 b thrust the pins 152 a, 152b out from the holes 123 a′, 123 b′ and the lateral angular sectors 121a, 121 b are pushed once again by the respective elastic elements 128 a,128 b towards the middle plane M of the drum 100.

Thereafter, the transfer member 500 picks the reinforced annularanchoring structure 15 up and the drum 100 is contracted until theoperative configuration shown in FIG. 8 is reached. Such a radialcontraction is produced by a further radial movement of the lateralangular sectors 121 a, 121 b in a radially inward direction and, fromthe time when the latter go into radial abutment on the intermediateangular sectors 111, from a simultaneous radial movement of theintermediate angular sectors 111 in a radially inward direction.

The transfer member 500 can thus withdraw the reinforced annularanchoring structure 15 from the drum 100, which is thus ready to proceedwith the looping of another annular anchoring structure according to theprocess described above.

The Applicant estimates for the entire looping process described above acycle time of about 40-50 seconds.

Of course, a man skilled in the art can bring further modifications andvariants to the invention described above in order to satisfy specificand contingent application requirements, said variants and modificationsin any case being within the scope of protection as defined by thefollowing claims.

The invention claimed is:
 1. A drum for looping annular anchoringstructures in a process for building tyres for vehicle wheels,comprising a radially expandable/contractible intermediate annularportion and, in a position axially adjacent to opposite axial ends ofsaid intermediate annular portion, a pair of radiallyexpandable/contractible lateral annular portions, the intermediateannular portion and the lateral annular portions being configured tosupport a loop, wherein each lateral annular portion of said pair oflateral annular portions comprises a plurality of circumferentiallyadjacent first angular sectors, wherein each of the circumferentiallyadjacent first angular sectors is capable of a synchronous radialmovement and a synchronous axial displacement to cause a thrustingstress imparted by the respective lateral annular portion to turn up anend edge of the loop on an annular anchoring structure arranged at theintermediate annular portion; wherein the drum is configured so thatduring the turning up, the annular anchoring structure is not rotated.2. The drum according to claim 1, wherein said intermediate annularportion comprises a plurality of circumferentially adjacent secondangular sectors capable of being moved radially synchronously with eachother.
 3. The drum according to claim 2, wherein said intermediateannular portion comprises, in a radially inner position with respect toeach of said second angular sectors, a first elastic element acting toradially thrust a respective second angular sector.
 4. The drumaccording to claim 1, wherein each of said first angular sectors isslidably associated with a radially outer surface of a radially movablesupport body.
 5. The drum according to claim 3, wherein each of saidsecond angular sectors is kept in a radial contracted position againstsaid radial thrust by a pair of said first angular sectors axiallyopposite to each other.
 6. The drum according to claim 1, wherein eachof said first angular sectors comprises a second elastic element actingto axially thrust an axially outer end thereof.
 7. The drum according toclaim 1, wherein each of said first angular sectors comprises a contactelement associated with an axially inner end thereof.
 8. The drumaccording to claim 1, comprising a locking assembly for stopping theaxial movement of said first angular sectors.
 9. The drum according toclaim 8, wherein said locking assembly comprises: a pair of holes formedon said radially outer surface of said support body; a pin associatedwith a respective first angular sector; and a third elastic elementacting between said pin and the respective first angular sector so that,in an axial locking condition of said first angular sector, a free endportion of said pin is housed inside one of said holes and, in an axialunlocking condition of said first angular sector, said free end portionof said pin is outside of said hole.
 10. The drum according to claim 8,wherein said locking assembly comprises, at an axially outer end of saidfirst angular sectors: a contrast ring; and a plurality of balancinglevers, each balancing lever having a first end pivoted at an axiallyouter end of a respective first angular sector and a second endconfigured to cooperate with said contrast ring when said first angularsector is in a condition of maximum expansion.
 11. The drum according toclaim 10, wherein said locking assembly comprises: a pair of holesformed on said radially outer surface of said support body; a pinassociated with a respective first angular sector; and a third elasticelement acting between said pin and the respective first angular sectorso that, in an axial locking condition of said first angular sector, afree end portion of said pin is housed inside one of said holes and, inan axial unlocking condition of said first angular sector, said free endportion of said pin is outside of said hole; wherein, when said secondend of said balancing lever is not in contact with said contrast ring,said first angular sector is in said axial unlocking condition, and whensaid second end of said balancing lever is in contact with said contrastring, said first angular sector reaches said axial locking condition.12. The drum according to claim 8, comprising an unlocking assembly forunlocking the axial movement of said first angular sectors.
 13. The drumaccording to claim 12, wherein said locking assembly comprises: a pairof holes formed on said radially outer surface of said support body; apin associated with a respective first angular sector; and a thirdelastic element acting between said pin and the respectice first angularsector so that, in an axial locking condition of said first angularsector, a free end portion of said pin is housed inside one of saidholes and, in an axial unlocking condition of said first angular sector,said free end portion of said pin is outside of said hole; wherein saidunlocking assembly comprises a spigot configured to expel said free endportion of said pin from said hole when said first angular sector isradially contracted until a condition of maximum contraction is reached.14. The drum according to claim 13, wherein said spigot is arranged in aradially outer position with respect to a guide bar provided for guidingthe radial movement of said first angular sector.
 15. The drum accordingto claim 1, comprising, at each of said opposite axial ends of saidintermediate annular portion: a screw-lead nut coupling; and a pluralityof levers each lever having a first end pivoted at a respective lead nutand a second end pivoted at the support body.
 16. The drum according toclaim 15, wherein said screw comprises a first axial portion with aright-handed thread and a second axial portion with a left-handedthread, or vice-versa.
 17. The drum according to claim 1, wherein anelastic thrust is exerted on each of said first angular sectors toachieve an axial displacement thereof towards a middle plane of thedrum.